1. Field of the Invention
The invention relates to push-to-talk devices, and more particularly, to a method for implementing push-to-talk over a SIP VoIP system using a network infrastructure.
2. Description of the Prior Art
Traditionally, push-to-talk (PTT) technology is most commonly seen in walkie-talkie devices. A button of the walkie-talkie is pushed and held down while a user talks into a microphone of the walkie-talkie. Other users are able to listen through a speaker on their own walkie-talkies. With the development of mobile phone networks, mobile phone operators such as 3G and GPRS network operators are starting to offer PTT services along with their mobile phone plans.
Recently, there has been a dramatic increase in the popularity of computer local area networks (LANs), particularly wireless LANs. This, together with the increasing numbers of people who have Internet access, has also brought about the rise of Voice over Internet Protocol (VoIP) communication. Session Initiation Protocol (SIP) is one of the real-time communication protocols used for VoIP, and supports other multimedia applications such as instant messaging, video, online games, and so on.
Unfortunately, there is currently no way to use the extensive computer LANs for performing PTT communication over SIP VoIP. Thus, users wishing to communicate through PTT have to use traditional walkie-talkies or use mobile phones that offer this special service. Traditional walkie-talkies have a limited communication range, whereas a charge is usually incurred for using a mobile phone to perform PTT communication. Moreover, neither makes use of the Internet, which is an enormous network connecting people all over the world.